Conditioner for soft pad and method for manufacturing same

ABSTRACT

The present invention relates to a conditioner for a chemical-mechanical planarization (CMP) pad, which is used in a CMP process that is part of a semiconductor element manufacturing process, and more particularly, to a conditioner for a soft pad, and a method of manufacturing the same, wherein the conditioner can be used under CMP conditions using a slurry having a small amount of polishing particles, and/or a porous pad having comparatively low hardness and very high porosity.

CROSS REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

This patent application is a National Phase application under 35 U.S.C.§371 of International Application No. PCT/KR2012/001673, filed Mar. 7,2012, which claims priority to Korean Patent Application No.10-2011-0019803 filed Mar. 7, 2011, entire contents of which areincorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a conditioner for a chemical-mechanicalplanarization (CMP) pad, which is used in a CMP process that is part ofa semiconductor element manufacturing process.

2. Description of the Related Art

CMP techniques for use in semiconductor devices are used to planarize athin film, such as an insulating film or a metal film formed on asemiconductor wafer.

Typically, the kind of slurry used in a CMP process varies depending onthe planarization of oxides, tungsten, or copper, and the slurry maycontain polishing particles so as to mechanically planarize the wafer.In order to achieve chemo-mechanical polishing, an acidic solution maybe added. In particular, the polishing particles are responsible forpromoting mechanical wear on diamond particles of the conditioner. Thepolishing particles may primarily include silica or ceria, and theamount of the polishing particles may vary greatly depending on the kindof slurry and the conditions of use thereof.

The polishing particles are contained in an amount of about 1˜10 wt % inthe slurry, and are acidic or neutral depending on the kind of slurry.When such a slurry is used, a load applied to the conditioner is a forceof about 5˜14 pounds. Even when diamond particles are used, theserviceable life of the conditioner is approximately 5˜30 hr due to wearof the acute ends of the diamond particles used as cutting tips.

Optionally, there is provided a copper CMP process, that is performed atthe final step of a CMP process, for the polishing of a wafer. Thecopper CMP process is a process that is conducted under conditions inwhich the properties of a pad are very soft and a very low load of 3pounds or less is applied.

A pad for use in the copper CMP process is commonly exemplified by aFujibo pad, and a slurry for the Fujibo pad is a planarization slurryhaving 1% or less of polishing particles, and thus has a very lowprocess load in terms of the conditioner. Thus, the CMP process isperformed only when low wear resistance of the cutting tips of theconditioner is required.

For this reason, however, even when an electrodeposited conditioner,among other conventional CMP pad conditioners, is designed to have asmaller number of diamond particles, the edges of the diamond particlesand the acute edges of the cutting tips may easily tear the soft pad ormay deform the pores of the surface of the pad. Thus, the pad can nolonger be used and undesirably shortens the serviceable life of the pad.Furthermore, this makes it impossible to uniformly maintain the state ofthe pad during its usage, affecting the uniform control of the materialremoval rate of a wafer.

With the goal of solving the aforementioned problems, a CMP padconditioner has been developed, which is configured such that thesurface of a substrate thereof is projected in a predetermined form toprovide a plurality of protrusions which are coated with a diamondthin-film using chemical vapor deposition (CVD). In this regard, KoreanPatent No. 10-0387954 discloses a CMP pad conditioner, wherein aplurality of truncated pyramids with polygonal bases are formed upwardupwards at uniform heights on the surface of the substrate thereof andcoated with a diamond layer using CVD.

However, some limitations are imposed on manufacturing the conditionersin such a manner, in that the cutting tips are processed on thesubstrate thereof and then coated with a diamond layer using CVD, asdisclosed in the above patent. More specifically, an expensive apparatusis required to produce the diamonds, and the size of the chamber shouldbe enlarged to increase productivity, which is regarded as technicallydifficult and expensive. In the manufacturing cost of the diamondthin-film conditioner, the diamond coating cost is very high and thecoating time is 20˜40 hr, resulting in undesirably slow processingspeeds.

Thus, there is a need for a novel conditioner, which may solve theproblems associated with the electrodeposited conditioner and thediamond coated conditioner disclosed in the above patent, and may alsobe applied to a process, including a copper CMP process, underconditions using a very soft pad and a very low load of 3 pounds orless, or using a slurry having polishing particles in amounts as low as1% or less.

SUMMARY

Culminating in the present invention, intensive and thorough research,carried out by the present inventors aiming to solve the problemsencountered in the related art, led to development of a conditioner fora soft pad, which may solve the problems associated with anelectrodeposited conditioner and a diamond coated conditioner disclosedin the above patent, and may also be applied to a copper CMP process,etc.

Accordingly, an aspect of the present invention is to provide aconditioner for a soft pad and a method of manufacturing the same,wherein the conditioner may have a controlled structure depending on apredetermined pattern, so as to stably maintain the material removalrate of a wafer, and is configured such that the manufacturing cost maybe drastically reduced.

Another aspect of the present invention is to provide a conditioner fora soft pad and a method of manufacturing the same, wherein there is noneed for a diamond coating process, and thus the material for asubstrate useful in manufacturing the conditioner is not limited so longas it satisfies wear resistance.

Still another aspect of the present invention is to provide aconditioner for a soft pad and a method of manufacturing the same,wherein cutting tips of the conditioner have no diamond layer, thusobviating a CVD diamond coating process, thereby shortening themanufacturing process and reducing the manufacturing cost, resulting inimproved productivity.

Yet another aspect of the present invention is to provide a conditionerfor a soft pad and a method of manufacturing the same, wherein there isno need for a diamond coating process, and thus an additional processfor controlling the size of the conditioner, after coating it withdiamond, may be omitted, unlike conventional diamond coated CMP padconditioners, thus reducing defect rates.

The aspects of the present invention are not limited to the foregoing,and other embodiments, which are not mentioned herein, will be clearlyunderstood to those skilled in the art from the following description.

In order to accomplish the above aspects, the present invention providesa conditioner for a soft pad, comprising a substrate having at least oneflat surface; and a plurality of cutting tips formed to protrude upwardon parts, or on all surfaces, of the substrate and spaced apart fromeach other.

In an embodiment, the substrate and the cutting tips are made of thesame material, including any one selected from among a carbide material,a ceramic material, including SiC or Si₃N₄, and a composite ceramicmaterial, including one or both of SiO₂ and Al₂O₃.

In an embodiment, the cutting tips are configured such that upper endsthereof are provided in the form of a plane, a line, or a point.

In an embodiment, when the upper ends of the cutting tips are providedin the form of a plane parallel to the surface of the substrate, theoverall shape thereof can be any one or more selected from among acylindrical shape, a polyprismoidal shape, a truncated conical shape,and a truncated pyramidal shape.

In an embodiment, the cutting tips are configured to be the same as inone or more selected from among the overall shape, the protrusionheight, and the separation interval.

In an embodiment, the conditioner for a soft pad is applied to a CMPprocess, including a copper CMP process, under one or both conditions ofusing a load of 3 pounds or less, and using a slurry having 1% or lesspolishing particles.

In addition, the present invention provides a method of manufacturingthe conditioner for a soft pad as in any one of claims 1 to 6,comprising preparing a substrate having a thickness greater than aprotrusion height of cutting tips; and forming a plurality ofprotrusions at a predetermined interval on one surface of the substratedepending on a predetermined pattern, thus forming cutting tips.

In an embodiment, the protrusions formed in forming the cutting tips areconfigured such that the upper ends thereof are provided in the form ofa plane, a line, or a point.

In an embodiment, forming the cutting tips is performed using both anetching process and any one of the micromachining processes selectedfrom cutting wheel processing, end milling, milling cutter processing,drilling, tapping, and laser processing, or using either the etchingprocess or any one of the micromachining processes.

In an embodiment, the etching process includes subjecting the surface ofthe substrate, on which the protrusions will be formed, tophotolithography, then extending part or all of the protrusion height ofthe protrusions at a predetermined interval by etching, wherein whenpart of the protrusion height is protruded, forming the rest of theheight of the protrusions, which are partially protruded, using any onemicromachining process as above, is further performed.

In an embodiment, when the part of the protrusion height is extended,the protrusion height of the protrusions extended by the etching is1˜50% of the total protrusion height.

In an embodiment, the method further comprises subjecting one surface ofthe substrate, before formation of the cutting tips, to precisiongrinding and lapping.

One or more embodiments of the present invention has the followingsuperior effects.

In a conditioner for a soft pad and a method of manufacturing the same,according to the present invention, the conditioner has a controlledstructure depending on a predetermined pattern so as to stably maintainthe material removal rate of a wafer, and furthermore, the manufacturingcost can be drastically reduced.

Also, in a conditioner for a soft pad and a method of manufacturing thesame, according to the present invention, there is no need for a diamondcoating process, and thus the material for a substrate useful inmanufacturing the conditioner is not limited so long as it satisfieswear resistance.

Also, in a conditioner for a soft pad and a method of manufacturing thesame, according to the present invention, cutting tips of theconditioner have no diamond layer, thus obviating the need of a CVDdiamond coating process, thereby shortening the manufacturing processand reducing the manufacturing cost, resulting in improved productivity.

Also, in a conditioner for a soft pad and a method of manufacturing thesame, according to another embodiment of the present invention, there isno need for a diamond coating process, and thus an additional processfor controlling the size of the conditioner after coating it withdiamond can be omitted, unlike conventional diamond coated CMP padconditioners, thus reducing defect rates.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a graph of the measurement results for pad wear rates(PWR) in a copper CMP process using a conditioner for a soft padaccording to an example of the present invention, a known CVD diamondcoated conditioner (comparative example), and an electrodepositedconditioner; and

FIG. 2 illustrates the surface of a conditioned Fujibo pad after acopper CMP process using a conditioner for a soft pad according to anexample of the present invention, a known CVD diamond coated conditioner(comparative example), and an electrodeposited conditioner.

DETAILED DESCRIPTION

Although the terms used in the description of the present invention areselected from generally known and used terms, some of the termsmentioned in the description of the present invention have been selectedby the applicant, the detailed meanings of which should be understoodnot simply by the actual terms used, but by the meaning of each term asdesired in the detailed description of the invention and/or inconsideration of the meanings used.

As used herein, the term “cutting tip” means a single protrusion formedon the surface of a substrate as a cutting unit, and may be used withthe same meaning as a “protrusion” in some cases.

Also, as used herein, the term “soft pad” means a pad for use in a CMPprocess under the conditions of using a load of 3 pounds or less and/orusing a slurry having 1% or less polishing particles.

Hereinafter, a detailed description will be given for the technicalconfiguration of the present invention with reference to embodimentsillustrated in the appended drawings.

However, the present invention is not limited to such embodiments, andmay be modified. Throughout the description, the same reference numeralsused to describe the present invention designate the same elements.

The first technical feature of the present invention is a conditionerfor a soft pad, which has a controlled structure depending on apredetermined pattern, so as to stably maintain the material removalrate of a wafer. The conditioner for a soft pad is also configured suchthat the manufacturing cost may be drastically reduced due to thematerial for a substrate useful in manufacturing a conditioner are notlimited, so long as they satisfy wear resistance, without the need for adiamond coating process.

Therefore, the conditioner for a soft pad according to the presentinvention includes a substrate having at least one flat surface and aplurality of cutting tips formed to protrude upward on part, or all, ofthe surface thereof, and spaced apart from each other.

The substrate and the plurality of cutting tips, which constitute theconditioner for a soft pad, may be integrally formed so as to derivefrom the same material, and the material is not limited so long as itsatisfies wear resistance, and may be any one selected from a carbidematerial, a ceramic material, including SiC or Si₃N₄, and a compositeceramic material, including one or both of SiO₂ and Al₂O₃.

The cutting tips may be configured such that the upper ends thereof areprovided in the form of a plane, a line, or a point so long as they areformed to protrude upward on the surface of the substrate depending onthe predetermined pattern. In the case where the upper ends of thecutting tips are provided in the form of a plane parallel to the surfaceof the substrate, the overall shape thereof may include any one or moreselected from a cylindrical shape, a polyprismoidal shape, a truncatedconical shape, and a truncated pyramidal shape.

Also, the cutting tips may be configured such that they may beindividually different from each other in overall shape, protrusionheight, and separation interval, or may be classified into severalgroups that are different from each other in overall shape, protrusionheight, and separation interval, depending on the controllingconditions/intentions of a worker. However, in the case where thecutting tips are configured to be the same in one or more selected fromthe overall shape, protrusion height, and separation interval, it may beso long as they are in terms of stably maintaining the material removalrate of the wafer.

As apparent from the following test examples, in the case where theconditioner for a soft pad according to the present invention is appliedto a CMP process, including a copper CMP process, requiring preciseuniformity under conditions of using a load of 3 pounds or less and/orusing a slurry having 1% or less polishing particles, the conditioner ofthe present invention may exhibit performance equal to or greater thanthat of a conventional CMP pad conditioner coated with a diamond layer.

The second technical feature of the present invention is a method ofmanufacturing the conditioner for a soft pad, wherein the cutting tipsof the conditioner have no diamond layer, thus obviating a CVD diamondcoating process, thereby shortening the manufacturing process andreducing the manufacturing cost. Also, an additional process necessaryto control the size of the conditioner after coating it with diamond maybe omitted, unlike conventional diamond coated CMP pad conditioners,allowing reductions in defect rates and considerable improvements inproductivity.

Thus, the method of manufacturing the conditioner for a soft padaccording to the present invention includes preparing a substrate havinga thickness greater than the protrusion height of the cutting tips; andforming a plurality of protrusions at a predetermined interval on onesurface of the substrate depending on a predetermined pattern, thusforming the cutting tips.

The plurality of protrusions formed at the step of producing the cuttingtips may be configured such that the upper ends thereof may be providedin the form of a plane, a line, or a point. Thus, the protrusion height,overall shape, and separation interval of and between the protrusionsare not limited so long as they are controlled depending on thepredetermined pattern.

Furthermore, the step of producing the cutting tips may be performedusing both an etching process and any one micromachining processselected from cutting wheel processing, end milling, milling cutterprocessing, drilling, tapping, and laser processing, or may be conductedby either of the etching process or the micromachining process.

The etching process includes subjecting the surface of the substrate, onwhich the protrusions will be formed, to photolithography, and extendingpart or all of the protrusion height of the protrusions at apredetermined interval by etching. As such, known dry etching and wetetching processes may be utilized.

In the case where part of the protrusion height is extended by etching,forming the rest of the height of the protrusions, which are partiallyextended, may be further carried out using any one micromachiningprocess as above. When the step of producing the cutting tips isperformed using both the etching process and the micromachining processin this way, the etching process may be conducted first, followed by themicromachining process.

Conversely, in the case where part of the protrusion height of thecutting tips is extended by etching at the step of producing the cuttingtips, the protrusion height of the protrusions extended by etching maybe 1˜50% of the total protrusion height of the cutting tips.

In some cases, in order to more precisely control the overall shape,protrusion height, etc. of the cutting tips, a step of subjecting onesurface of the substrate to precision grinding and lapping may befurther performed before the step of producing the cutting tips.

EXAMPLES Example 1

In order to ensure surface flatness, a Si₃N₄ substrate having a flatnesstolerance of 3 mm±0.002 mm or less was prepared via lapping. To producecutting tips, depending on a predetermined pattern, micromachining wasperformed using a polisher, and protrusions were processed such that thewidth and length were 50 μm, and the height was 50 μm, and the number ofprotrusions was 10,000, thereby completing the conditioner for a softpad.

Comparative Example 1

To form a diamond coating on a substrate having protrusions formed usingthe same process as in Example 1, the substrate having protrusions waspretreated using an ultrasonic device so that diamond powder having asize of 1˜2 μm was fed in to facilitate diamond nucleation in order toenhance adhesion between the diamond nuclei and the thin film. Thediamond thin film was grown for 10 hr using a thermal filament process(i.e., a CVD process), thereby manufacturing a CVD diamond coatedconditioner (CVD Disk).

Test Example 1

Using the conditioner for a soft pad of the Example 1, the CVD diamondcoated conditioner of the Comparative Example 1, and a commerciallyavailable electrodeposited conditioner, a copper CMP process wasperformed for 31 hr using a Fujibo pad and a planarization slurry having1% or less polishing particles. The resulting pad wear rate (PWR) perconditioner was measured. The results are illustrated in FIG. 1.

As illustrated in FIG. 1, the electrodeposited conditioner decreased thePWR to 50% after 15 hr, but the CVD diamond coated conditioner and theconditioner for a soft pad, according to the present invention,maintained the PWR even after 30 hr.

Test Example 2

The surface of the Fujibo pad conditioned using each conditioner aboveafter performing Test Example 1 was observed via incremental andsequential magnification, and was compared to the initial CMP process.The surface images are illustrated in FIG. 2.

As illustrated in FIG. 2, when using the electrodeposited conditioner,the surface of the soft Fujibo pad was bitten, and the PWR wasdrastically lowered. The surface of the pad using the CVD diamond coatedconditioner was considerably similar to that of the pad using theconditioner for a soft pad according to the present invention.

Test Example 3

One hundred (100) diamond particles and one hundred (100) cutting tipswere chosen as samples at a certain portion of each conditioner, and theexposed heights of the samples, before and after Test Example 1, weremeasured. The results are shown in Table 1 below.

TABLE 1 Exposed Heights, Before and After CVD ElectrodepositedConditioner diamond coated Height conditioner for soft pad conditionerBefore 57.1 μm (31.4-97.2) 50.7 μm (49.9-51.6) 50.7 μm (49.7-51.3) Use(Max- Min) After 55.8 μm (31.1-94.5) 50.2 μm (49.6-51.1) 50.1 μm(49.3-51.0) Use (Max- Min) Wear  2.3 μm  0.5 μm  0.6 μm rate

As is apparent from Table 1, there were no significant changes in theexposed heights in all the conditioners. However, the electrodepositedconditioner had significant changes in the Max-Min values (˜3-fold),whereas the CVD diamond coated conditioner and the conditioner for asoft pad, according to the present invention, had no significant changesin Max-Min values. This is thought to be because the pad was severelyrubbed by the smaller number of working diamond particles of theelectrodeposited conditioner.

As apparent from the results of Test Examples 1-3, wherein theconditioner for a soft pad according to the present invention is used inthe copper CMP process, a performance equal to or greater than that ofthe CVD diamond coated conditioner can be exhibited.

Therefore, in the case where the conditioner for a soft pad according tothe present invention is applied to a CMP process, including a copperCMP process, under conditions of using a load of 3 pounds or less and/orusing a slurry having 1% or less polishing particles, the performancethereof can be seen to be equal to or greater than that of aconventional diamond coated CMP pad conditioner.

Reference Test Example

The conditioner for a soft pad of the Example 1 and the CVD diamondcoated conditioner of the Comparative Example 1 were subjected to W2000CMP using IC 1010 for 5 hr under a load of 10 lbf, and the heights ofthe cutting tips of the conditioners were measured before and after theabove process. The results are shown in Table 2 below.

TABLE 2 Before and After Heights of the Cutting Tips Conditioner for CVDDiamond Soft Pad Coated Conditioner Average Height of Cutting Tips 50.750.7 Before Use Average Height of Cutting Tips 41.9 49.7 After Use WearSpeed of Cutting Tips 1.76 μm/hr 0.2 μm/hr

As apparent from Table 2, the conditioner for a soft pad, according tothe present invention, having no diamond coating is difficult to applyto a process using a slurry having polishing particles in amounts ashigh as about 6%, and high loads as in the W2000 CMP process because ofthe high wear speeds of the cutting tips thereof.

Although the embodiments of the present invention have been disclosedfor illustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions, and substitutions are possible,without departing from the scope and spirit of the invention asdisclosed in the accompanying claims.

What is claimed is:
 1. A conditioner for a soft pad, comprising: asubstrate having at least one flat surface; and a plurality of cuttingtips formed to protrude upward on part or all of the surface of thesubstrate and spaced apart from each other.
 2. The conditioner of claim1, wherein the substrate and the cutting tips are made of a samematerial, including any one selected from the group consisting of acarbide material, a ceramic material including SiC or Si₃N₄, and acomposite ceramic material including one or both of SiO₂ and Al₂O₃. 3.The conditioner of claim 1, wherein the cutting tips are configured suchthat upper ends thereof are provided in a form of a plane, a line, or apoint.
 4. The conditioner of claim 3, wherein when the upper ends of thecutting tips are provided in the form of a plane parallel to the surfaceof the substrate, with an overall shape thereof having any one or moreshapes selected from the group consisting of a cylindrical shape, apolyprismoidal shape, a truncated conical shape, and a truncatedpyramidal shape.
 5. The conditioner of claim 1, wherein the cutting tipsare configured to be the same as in one or more selected from the groupconsisting of an overall shape, a protrusion height and a separationinterval.
 6. The conditioner of claim 1, wherein the conditioner for asoft pad is applied to a chemical-mechanical planarization (CMP) processincluding a copper CMP process under one or both conditions of using aload of three (3) pounds or less and using a slurry having 1% or less ofpolishing particles.
 7. A method of manufacturing a conditioner for asoft pad, the method comprising: preparing a substrate having athickness greater than a protrusion height of the cutting tips; andforming a plurality of protrusions at a predetermined interval on onesurface of the substrate depending on a predetermined pattern, thusproducing the cutting tips.
 8. The method of claim 7, wherein theprotrusions formed in producing the cutting tips are configured suchthat upper ends thereof are provided in a form of a plane, a line or apoint.
 9. The method of claim 7, wherein forming the cutting tips isperformed using both an etching process and any one micromachiningprocess selected from the group consisting of cutting wheel processing,end milling, milling cutter processing, drilling, tapping, and laserprocessing, or using either the etching process or the any onemicromachining process.
 10. The method of claim 9, wherein the etchingprocess includes subjecting the surface of the substrate, on which theprotrusions will be formed, to photolithography, then extending part orall of the protrusion height of the protrusions at a predeterminedinterval by etching, wherein when part of the protrusion height isprotruded, forming a rest of the height of the protrusions which arepartially protruded, using any one micromachining process.
 11. Themethod of claim 10, wherein when the part of the protrusion height isprotruded, the protrusion height of the protrusions extended by theetching is 1˜50% of a total protrusion height.
 12. The method of claim7, further comprising subjecting one surface of the substrate, beforeformation of the cutting tips, to precision grinding and lapping. 13.The method of claim 7, wherein the substrate and the cutting tips aremade of a same material, including any one selected from the groupconsisting of a carbide material, a ceramic material including SiC orSi3N4, and a composite ceramic material including one or both of SiO2and Al2O3.
 14. The method of claim 7, wherein the cutting tips areconfigured such that upper ends thereof are provided in a form of aplane, a line or a point.
 15. The method of claim 14, wherein when theupper ends of the cutting tips are provided in the form of a planeparallel to the surface of the substrate, with an overall shape thereofhaving any one or more shapes selected from the group consisting of acylindrical shape, a polyprismoidal shape, a truncated conical shape,and a truncated pyramidal shape.
 16. The method of claim 7, wherein thecutting tips are configured to be the same as in one or more selectedfrom the group consisting of an overall shape, a protrusion height and aseparation interval.
 17. The method of claim 7, wherein the conditionerfor a soft pad is applied to a chemical-mechanical planarization (CMP)process including a copper CMP process under one or both conditions ofusing a load of three (3) pounds or less and using a slurry having 1% orless polishing particles.